Dermatitis

Causes of dermatitis

Many causes of dermatitis are unknown while some skin conditions have a distinct cause. Dermatitis is an umbrella term for disorders of the skin however the condition has a number of categories which explain the possible triggers or factors that result in skin problems.

Contact dermatitis
This type of dermatitis is caused by contact with an irritant or allergen. Common irritants that trigger contact dermatitis include:

• Soaps
• Detergents
• Cleaning products

Common allergens include:

• Cosmetics
• Metals (such as nickel)
• Rubber (latex)
• Plants (e.g. poison ivy)
• Weeds
• Jewellery

Dermatitis caused by an irritant usually takes a greater amount of contact with the specific irritant than for an allergen. An allergen can trigger dermatitis after brief exposure and can remain an allergen for life.

Neurodermatitis
This type of dermatitis usually develops when a skin irritation causes someone to rub or scratch the affected area repeatedly. Neurodermatitis commonly affects the ankles, wrists, arms and neck. Neurodermatitis has an association with skin conditions such as eczema or psoriasis.

Seborrheic dermatitis
This causes a red rash with oily scales usually on the scalp. People with oily skin or hair are commonly affected by seborrheic dermatitis and the condition can be triggered when physically stressed. People with Parkinson's disease can suffer with this type of dermatitis.

Stasis dermatitis
An accumulation of fluid in the tissue under the skin can interfere with the blood's ability to nourish it. This places extra pressure on the skin from underneath resulting in dermatitis. Stasis dermatitis typically affects the lower leg and people with varicose veins or circulatory problems may suffer with the condition.

Atopic dermatitis/eczema
The exact cause of this condition is unknown but it runs in families who suffer with asthma or hay fever. Typically beginning in childhood, a combination of dry skin and a problem with the function of the immune system can trigger a flare up. Exposure to allergens or irritants and stress can all exacerbate the condition.

Perioral dermatitis
The cause of this type of dermatitis is unclear but it affects the skin around the mouth and nose in the same way as rosacea, acne and seborrheic dermatitis. Cosmetics, dental products containing fluoride and corticosteroid creams may trigger the condition.

Symptoms of dermatitis

Dermatitis has a variety of symptoms including:

• Dry skin
• Itchy skin
• Flaky skin
• Red skin
• Inflammation
• Rashes
• Spots
• Blisters
• Papules (small bumps)
• Lesions
• Localised burning
• Scabbing

The severity of symptoms can range from mild to severe and may last for days, weeks or months.

Diagnosis of dermatitis

A GP will diagnose dermatitis based on a physical examination of the skin and asking questions about medical problems which run in the family such as asthma or hay fever. They may also question you about environmental factors you are exposed to such as chemicals or toxins.

Some types of dermatitis have no known cause but the GP may refer you for skin patch tests to rule out certain irritants and allergens. A patch test involves placing small patches on the skin which contain common causes or dermatitis to see if a rash develops. In some cases, you may require a blood allergy test or a skin biopsy to rule out other skin diseases.

Related terms

Rash
Eczema
Psoriasis
Urticaria
Skin